Potential Anti-Inflammatory Components of Rhododendron molle G. Don Leaf Extracts in LPS-Induced RAW 264.7

As a traditional Chinese medicine, Rhododendron molle G. Don has a long history of treating rheumatoid arthritis. In this study, RAW 264.7 cells induced by lipopolysaccharide (LPS) were established as cell inflammatory model to evaluate the anti-inflammatory activity of chloroform extract from R. molle leaves (CERL), ethyl acetate extract from R. molle leaves (EERL) and butanol extract from R. molle leaves (BERL) and analyze the potential anti-inflammatory components of R. molle. Potential anti-inflammatory components analysis of CERL were performed by HPLC and UHPLC-Q-TOF-MS. Prediction of potential anti-inflammatory components by molecular docking experiments. Compared with negative control group, 25 μg/mL CERL could reduce the release level of NO by 62 %, and the mRNA expression levels of COX-2, IL-6, IL-1β and TNF-α were reduced by 69.74 %, 86.25 %, 77.94 % and 56.80 %, respectively. Western-Blot showed similar results. CERL, EERL and BERL exerted their inhibitory activity in dose-dependent manner. All results showed that the higher the concentration, the better the anti-inflammatory activity. CERL showed the best inhibitory activity, the second was EERL, and then was BERL. 21 terpenoids and 4 flavonoids were identified in CERL by UHPLC-Q-TOF-MS. Molecular docking results showed that triterpenoids in CERL had better interaction with target proteins (TNF-α, IL-1β). It indicated that triterpenoids may be potential anti-inflammatory components of R. molle leaves. This study explored the anti-inflammatory activities of CERL, EERL, BERL, which laid a foundation for further promoting the clinical application of R. molle.